15,000 fans are expected to watch one of the world's biggest girl groups, Little Mix play at Caldicot Castle on Thursday - more than the entire population of the town.
The band is made up of former X-Factor contestants Perrie Edwards, Jesy Nelson, Leigh-Anne Pinnock and Jade Thirlwall
Gates open from 16:00 with Little Mix expected to take to the stage at 20:30 following performances from supporting acts Sheppard and Louisa Johnson.
Visitors have been warned to allow extra time for security checks and to expect a strong police presence on site.
Searches will take place on entry, with organisers requesting that fans bring small bags only.
Motorists have been advised that Church Road, one of the main routes into Caldicot's town centre, will be closed between 15:00 and 23:00.
A designated parking and drop-off point will be available at the David Broome Event Centre in nearby Crick - a five minute walk from the concert area.
The car park will open two hours before the gate time and vehicles cannot be left overnight.
Motorists are advised to access the parking fields by leaving the A48 at Crick and travelling down Crick Road.
Anyone coming from the west of Newport should be aware that the M4 Brynglas Tunnels will be closed westbound from 20:00. Diversions will see people leave the M4 as Junction 24 before rejoining at Junction 28.